Pigment granulates for coloring building materials

ABSTRACT

The invention pertains to pigment granulates for the coloring of asphalt, bitumen, bituminous materials, tar, and plastics as well as processes to manufacture such granulates. The mixture to be granulated comprises a mixture containing one or more pigments, at least one agent to promote the coloring and distribution in homopolar media and/or at least one dispersant for polar systems as well as one or more solvents if necessary.

[0001] The invention pertains to pigment granulate for the coloring ofhomopolar media, like asphalt, bitumen, bituminous materials, tar, andplastics, and processes for the manufacture of such granulates.

[0002] At present, in addition to organic pigments, inorganic pigments,especially those based on different iron oxides, are also used to colorhomopolar materials, especially asphalt and plastics. Compared topowders and pastes, pigment granulates exhibit very considerableadvantages in this regard, for example in their handling, theirprevention of dust and the like, but also in regard to their dispersingproperties.

[0003] The use of aqueous carbon preparations (containing 30 to 80%water) as pearl granulates for coloring in the cement industry is knownfrom DE-A1 29 08 202. This process cannot be applied to other pigments,and granulates with such water contents are fundamentallydisadvantageous, also for applications involving asphalt and plastics.

[0004] The granulation of pigments together with binders through spraygranulation is known from DE-A1 29 40 156. Pigment granulates producedin this way are used to manufacture inks, to color plastics, lacquers,and the like. There is no connection to the coloring of buildingmaterials, asphalt, and the like.

[0005] Color granulates for building materials containing more than 5 to50% by weight of water are known from EP-A2 0 191 278.

[0006] EP-A1 0 567 882 describes pelletized, compacted, and sprayedgranulates containing binders, such as especially machine oil, wax,paraffin, and the like, which are to be used to color asphalt, amongother things. In addition to the binders, substances like ligninsulfonate, molasses, starch, and the like can be used. According to thisdisclosure, substances like lignin sulfonate alone cannot be used asbinders.

[0007] In the context of this description, “granulates” means everymaterial whose mean grain size in comparison to the original material isincreased by a treatment stage. Therefore, “granulates” means not onlyspray granulates and compacting granulates but, for example, alsoproducts of a moist treatment with subsequent pulverizing.

[0008] On account of their considerable advantages, in comparison topowders, pastes, and the like, granulates have been used for decades ona large scale industrially. Granulation has been accepted for a longtime for the processing of pigments as well.

[0009] Experience acquired with pigment granulates in other areas cannotsimply be transferred to the coloring of building materials, asphalt,and the like. In practice, granulates, which theoretically should bealmost perfectly suitable, often prove inadequate because they do notcombine all of the required properties.

[0010] Although often an excellent solidity of the granulate isachieved, which counteracts its destruction during packaging andtransport and restricts the production of dust, on the other hand, itsdispersability can be impaired, resulting in the desired homogeneouscoloring and the required color intensity not being achieved.

[0011] On the other hand, granulates with excellent color intensity andeasy dispersability are often too soft and already disintegrate beforethey are worked into the asphalt or plastic, which can result inincreased dust production, in residues in the packaging, in reducedflowability and in corresponding frequent incorrect dosages.

[0012] Of the various methods of granulation, spray granulation hasbecome generally accepted in practice, while, for example, fluidized bedgranulations, which is fully comparable theoretically, has not yetproduced any usable granulates.

[0013] Proposals have recently become known to forego granulatescompletely and, instead, to use coated powders. WO 97/20892 is given asan example. It remains to be seen whether in this way broad particlesize distributions due to clumping can be avoided and whether suchcoated powders can be used without producing the dust problems typicalof the prior art before pigment granulates were introduced.

[0014] In order to promote the dispersion and distribution of pigmentgranulates, wetting and binding agents are used which are chosen in sucha way that the granulate disintegrates with the desired dispersingeffect. For the coloring of homopolar media, such as especially asphaltand plastics, hydrophobic compounds, like oils and waxes, whichguarantee an adequate dispersability of the granulates in thehydrophobic application medium, are traditionally used as binders forthe mixture to be granulated. The disadvantages of mixtures to begranulated which are based on homopolar solvents are, first, the highcosts in comparison to a mixture based on water, for example, and,second, the fact that special technical devices and security measuresare required for the evaporating organic binders, like oils and waxeswhere granulates are spray dried.

[0015] Water-based wetting agent and binder mixtures, for whichwater-soluble wetting agents and binders, like lignin sulfonate and thelike, exhibit the disadvantage, however, the pigment cannot behomogeneously distributed in a homopolar application medium, likeasphalt, bitumen, or plastic. This result in an uneven coloring, whichis undesirable.

[0016] Therefore, an essential objective of the invention is to propose,against this background, a process for the coloring of homopolar media,like asphalt, bitumen, bituminous materials, tar, and plastics, by meansof pigment granulates which promotes the coloring by the pigments and atthe same time improves the dispersion of the pigment in a homopolarapplication medium. Another objective of the invention is to present aprocess which promotes the sprayability of the granulate.

[0017] The features defined in the independent claims achieve thisobjective.

[0018] Advantageous developments are described in the dependent claims.

[0019] The objective of the invention is solved by the pigments, inparticular iron oxides and/or soot pigments, and the traditional wettingand binding agents, also being mixed during the manufacture of thepigment granulates with at least one agent which promotes the coloringand the distribution of the pigment in a homopolar media and/or at leastone dispersing agent for polar systems. Surprisingly, it was found thatthe agents to promote the coloring and the distribution of the pigmentin a homopolar media in accordance with this invention act in such a waythat a lipophilic coating is produced on the granulate as a result ofwhich the dispersion and, therefore, the homogeneous distribution of thepigment in the homopolar media, like asphalt, bitumen, bituminousmaterials, tar, and plastics, is promoted and, consequently, also thecoloring of the homopolar media is promoted in an above-average manner.

[0020] Such an agent which promotes the coloring and the distribution ofthe pigment and which can be used to manufacture the inventive pigmentgranulate is preferably a wax or a mixture of several waxes. When usingwaxes, attention must be paid to the wax having both a high scratch andabrasion resistance. In a preferred embodiment of the invention, waxeswith these properties have a melting point in the 50° C. to 200° C.range, preferably 50° C. to 130° C.

[0021] It is irrelevant with this invention whether the waxes arenatural or synthetic in origin. Preferably, however, synthetic waxes areused, like polyalkylene waxes, especially polyethylene waxes,polyethylene glycol waxes, paraffin waxes, styrene acrylate waxes,polytetrafluoroethylene waxes, and the like.

[0022] With this invention, non-ionogenic waxes, waxes with anionicionogenity, waxes with cationic ionogenity and combinations of thesewaxes are used. Preferably, wax mixtures are used, in which case bothmixtures of waxes with anionic and/or cationic ionogenity or mixtures ofnon-ionogenic waxes as well as mixtures of non-ionogenic waxes and waxeswith anionic or cationic ionogenity can be used. Especially preferred,mixtures of polyethylene wax and styrene-acrylate wax or mixtures ofpolyethylene wax and paraffin wax can be used.

[0023] In order to increase the solid contents, especially of thepigment contents, in the mixture to be granulated, in accordance withthe invention, dispersing agents or dispersants for polar systems can beused which promote the liquefication of solid pigment after polarsolvents are added, such as water in particular, and the shaping of thegranulates, especially with spray drying. The latter is especiallyadvantageous if the aforesaid agents which promote the coloring and thedistribution of the pigment in homopolar media are contained in themixture to be granulated. With this preferred embodiment, a synergisticeffect results due to the fact that both the pigment contents in themixture to be granulated and the shaping of the granulates are increasedas well as the homogeneity of the coloring in the homopolar medium. Thedispersants can also be used advantageously, however, if none of theagents which promote coloring and distribution of the pigment in ahomopolar media are used because, for example, with spray drying theincrease in the pigment fraction in the pigment slurry to be sprayedresults in the spray costs being reduced substantially. As well, theagents which promote the coloring and the distribution of the pigment inthe homopolar media can also be used advantageously if the dispersantsfor polar systems are not used.

[0024] Dispersants within the scope of this invention are defined, as inthe Römpp Chemie Lexikon [Römpp Chemistry Lexicon], Georg Thieme Verlag[Georg Thieme Publishers], Stuttgart, N.Y., ninth edition, 1990, page1010, as agents which facilitate the dispersing of particles in asolvent by lowering the surface tension between the two components.

[0025] With this invention the dispersants for polar systems in themixture to be granulated can be chosen from hydrophilic and amphoteric,ionogenic, and non-ionogenic compounds. Preferably, these agents can bechosen from mono- or polyhydroxy compounds, mono- or polyhydroxy aminecompounds, (poly)carboxylates, polyacrylates, lignin sulfonates,sulfated polyglycol ethers, melamine formaldehyde condensates,naphthalene formaldehyde condensates, alkyl-, aryl, or alkylarylsulfonates, polyglycols, polyglycol derivatives, PVP, polyethers,phosphates, silicates, aluminates, borates, cellulose derivatives, orcombinations of these compounds.

[0026] Monohydroxy compounds include monovalent, primary, secondary, ortertiary, alkyl-substituted or non-substituted alcohols, such as, forexample, 1-propanol, 2-methyl-1-propanol, 2-methyl-2-propanol, and thelike. Alcohols from C₃ up are preferred. The polyhydroxy compounds usedin accordance with the invention include polyhydric alkyl-substituted ornon-substituted alcohols, for example diols, glycols, like ethyleneglycol and polyalkylene glycol, glycerine, sugar alcohols, like sorbitoland ionositol, trimethylol propane, and the like. Preferably,2-methyl-1-propanol and glycols are used in the case of this invention.

[0027] The monohydroxyamino compounds used as dispersants includemonovalent, primary, secondary, or tertiary, alkyl-substituted ornon-substituted amino alcohols, such as 2-amino-1-propanol,2-amino-1-butanol, 3-amino-1-propanol, 2-amino-2-methyl-1-propanol, andthe like. Amino alcohols from C₃ up are preferred. Polyhydricalkyl-substituted or non-substituted alcohols, such as, for example,2-amino-2-methyl-1,3-dihydroxy propane, and the like can be used asinventive polyhydroxy amine compounds. In a preferred embodiment of thisinvention, 2-amino-2-methyl-1-propanol is used.

[0028] Other compounds with relatively low molecular weights (preferablyC₁ to C₁₀₀, more preferably C₂ to C₅₀, most preferably C₃ to C₂₅), whichcarry one or more hydrophilic groups, can also be used. These can be NH₂and OH, but also ether groups, carboxylic groups, acid functions, andthe like, if necessary also in neutralized (salt) form.

[0029] The total quantity of the agents to promote the coloring and thedistribution of the pigment in homopolar media used in the inventiveprocess for the manufacture of pigment granulates is at least 0.01percent by weight, preferably 0.01 to 5 percent by weight, andespecially preferred 0.4 to 3.5 percent by weight, based on the totalquantity (weight) of the mixture to be granulated.

[0030] The total quantity (weight) of the dispersants for polar systemsused in the inventive process for the manufacture of pigment granulatesis at least 0.05 percent by weight, preferably 0.1 to 3 percent byweight, and especially preferred 0.25 to 1.7 percent by weight, based onthe total weight of the mixture to be granulated.

[0031] In accordance with the invention, the pigments can be mixed as apowder mixture or suspended in a solvent with at least one agent topromote the coloring and the distribution in homopolar media and/or atleast one dispersant for polar systems. The resulting mixtures can beproduced through compression, compacting, pressing, or briquetting,spraying, fluidized bed drying, or through pelletizing, or combinationsof the aforesaid processes. Preferably, spray processes (e.g., sprayingor fluidized bed drying)are used.

[0032] The use of granulates during mixing with homopolar media, likeasphalt, bitumen, bituminous materials, tar, and plastics, correspondsto the customary, known procedures.

[0033] The following four examples are intended to explain embodimentsof the invention. Four pigment granulates suitable for the inventiveprocess for the coloring of homopolar media, especially asphalt andplastics, were manufactured in accordance with the recipes presented inthe following tables: Pigment granulate mixture 1 Substance Percent byweight Fresh water 34.66 Polyacrylate 1.15 2-amino-2-methyl-1-propanol0.25 Iron oxide red 62.50 Sodium hydroxide solution (20%) 0.20 Wükonil ™LP 50 0.83 Südranol ™ 340 0.31 Wükonil ™ MS 30 0.10

[0034] Pigment granulate mixture 2 Substance Percent by weight Freshwater 35.31 Lignin sulfonate 0.5 2-amino-2-methyl-1-propanol 0.25 Ironoxide red 62.50 Sodium hydroxide solution (20%) 0.20 Ultralube ™ E 3400.83 Ultralube ™ MD 2000 0.41

[0035] Pigment granulate mixture 3 Substance Percent by weight Freshwater 32.5 Polyethylene propylene glycol 1.5 2-amino-2-methyl-1-propanol0.25 Iron oxide red 62.5 Sodium hydroxide solution (20%) 0.20 Wükonil ™LP 50 1.66 Südranol ™ 340 0.89 Wükonil ™ MS 30 0.50

[0036] Pigment granulate mixture 4 Substance Percent by weight Freshwater 33.42 Polyacrylate 1.15 2-amino-2-methyl-1-propanol 0.25 Ironoxide red 62.50 Sodium hydroxide solution (20%) 0.20 Ultralube ™ E 3401.66 Ultralube ™ MD 2000 0.82

[0037] The brand names in the above tables represent the following:Wükonil ™ LP 50: macroparaffin (anionic, melting range: 60° C.)Südranol ™ 340: polyethylene wax (anionic, melting range: 95° C.)Wükonil ™ MS 30: styrene-acrylate wax (anionic, melting range: >80° C.)Ultralube ™ MD 2000: polyethylene wax (non- ionogenic, melting range:127° C.) Ultralube ™ E 340: paraffin wax (anionic, melting range: 56°C.-58° C.)

1. Pigment granulate for the coloring of homopolar media, like asphalt,bitumen, bituminous materials, tar, and plastics, manufactured from amixture containing pigments, at least one agent to promote the coloringand the distribution of pigment in homopolar media and/or at least onedispersant for polar systems as well as solvents if necessary. 2.Granulate in accordance with claim 1, characterized by the agent topromote the coloring and the distribution of pigment in homopolar mediabeing chosen from the wax group.
 3. Granulate in accordance with claim2, characterized by the wax having a melting point in the 50° C. to 200°C. range.
 4. Granulate in accordance with claim 3, characterized by thewax having a melting point in the 50° C. to 130° C. range.
 5. Granulatein accordance with one of claims 2 to 4, characterized by the waxcontaining mixtures of non-ionogenic waxes and/or waxes with anionicionogenity and/or waxes with cationic ionogenity.
 6. Granulate inaccordance with one of claims 2 to 5, characterized by the waxcontaining a mixture of polyethylene wax and styrene-acrylate wax. 7.Granulate in accordance with one of claims 2 to 5, characterized by thewax containing a mixture of polyethylene wax and paraffin wax. 8.Granulate in accordance with one of the preceding claims, characterizedby the total quantity of the agent to promote the coloring and thedistribution of pigment in homopolar media ranging from 0.1 to 5 percentby weight based on the total quantity of the mixture to be granulated.9. Granulate in accordance with claim 8, characterized by the totalquantity of the agent to promote the coloring and the distribution ofpigment in homopolar media ranging from 0.4 to 3.5 percent by weightbased on the total quantity of the mixture to be granulated. 10.Granulate in accordance with claim 1, characterized by the dispersantfor polar systems being chosen from the group of mono- or polyhydroxycompounds, mono- or polyhydroxyamine compounds, (poly)carboxylates,polyacrylates, lignin sulfonate, sulfated polyglycol ethers, melamineformaldehyde condensates, naphthalene formaldehyde condensates, alkyl-,aryl, or alkylaryl sulfonates, polyglycols, polyglycol derivatives,polyethers, phosphates, silicates, aluminates, borates, cellulosederivatives, and combinations of these compounds.
 11. Granulate inaccordance with claim 10, characterized by the hydroxyamine compoundsincluding aminoethyl propanols.
 12. Granulate in accordance with claim10, characterized by the hydroxy compounds including methyl propanolsand glycols.
 13. Granulate in accordance with claim 1, characterized bythe total quantity of the dispersants for polar systems ranging from 0.1to 3 percent by weight based on the total quantity of the mixture to begranulated.
 14. Granulate in accordance with claim 13, characterized bythe total quantity of the dispersants for polar systems ranging from0.25 to 1.7 percent by weight based on the total quantity of the mixtureto be granulated.
 15. Granulate in accordance with one of the precedingclaims, characterized by the pigments being chosen from iron oxides andsoot pigments.
 16. Granulate in accordance with one of the precedingclaims, characterized by the solvent or solvents being polar solvents,such as water in particular.
 17. Process to manufacture a granulate inaccordance with one of the preceding claims, characterized by pigmentsbeing mixed as a powder mixture or as a suspension in a solvent with atleast one agent to promote the coloring and distribution in homopolarmedia and/or at least one dispersant for polar systems.
 18. Process inaccordance with claim 17, characterized by the granulate being producedby compression, compacting, pressing, or briquetting, by pelletizing,spraying, or fluidized bed drying, or by means of a combination of theaforesaid processes.